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Gera Shegalov commented on MAPREDUCE-4815: ------------------------------------------ The logic looks good to me now, [~l201514] Please add an entry to mapred-default.xml as suggested by [~xgong] to describe the difference between v1 and v2 and how you want to deal with upgrades. Outstanding nits in {{output.TestFileOutputCommitter}}: a bunch of fully qualified references to {{org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter.FILEOUTPUTCOMMITTER_ALGORITHM_VERSION}} In testRecoveryInternal 80-column limit is violated {code} conf.setInt( FileOutputCommitter.FILEOUTPUTCOMMITTER_ALGORITHM_VERSION, commitVersion); {code} probably easier to have it as: {code} conf.setInt(FileOutputCommitter.FILEOUTPUTCOMMITTER_ALGORITHM_VERSION, commitVersion); {code} > FileOutputCommitter.commitJob can be very slow for jobs with many output files > ------------------------------------------------------------------------------ > > Key: MAPREDUCE-4815 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-4815 > Project: Hadoop Map/Reduce > Issue Type: Bug > Components: mrv2 > Affects Versions: 0.23.3, 2.0.1-alpha, 2.4.1 > Reporter: Jason Lowe > Assignee: Siqi Li > Attachments: MAPREDUCE-4815.v10.patch, MAPREDUCE-4815.v11.patch, > MAPREDUCE-4815.v12.patch, MAPREDUCE-4815.v13.patch, MAPREDUCE-4815.v3.patch, > MAPREDUCE-4815.v4.patch, MAPREDUCE-4815.v5.patch, MAPREDUCE-4815.v6.patch, > MAPREDUCE-4815.v7.patch, MAPREDUCE-4815.v8.patch, MAPREDUCE-4815.v9.patch > > > If a job generates many files to commit then the commitJob method call at the > end of the job can take minutes. This is a performance regression from 1.x, > as 1.x had the tasks commit directly to the final output directory as they > were completing and commitJob had very little to do. The commit work was > processed in parallel and overlapped the processing of outstanding tasks. In > 0.23/2.x, the commit is single-threaded and waits until all tasks have > completed before commencing. -- This message was sent by Atlassian JIRA (v6.3.4#6332)